Comparison of gallic acid and catechin contents in five processed products of Rheum palametum

OBJECTIVE: To establish a HPLC method for the determination of gallic acid and catechin in Rheum palametum and to study the changes of gallic acid and catechin content in R. palametum during processing. METHOD: The contents of gallic acid and catechin were determined simultaneously by HPLC on the Zorbax Eclipse XDB-C18 (4.6 mm x 250 mm, 5 microm) column at 30 degrees C with gradient elution. The flow rate was 0.9 mL x min(-1) and the detecting wave-length was 277 nm. RESULT: There were obvious differences in contents of gallic acid and catechin between the crude herbal material and other four kinds of processed products of R. palametum. Compared to crude herbal material, the contents of gallic acid increased evidently increased in the five processed pieces, up to 139. 3% in the processed piece of braising with liquor. The contents of catechin were similar to gallic acid in the pieces of vinegar and the liquor sauted, but nearly not founded in the braising with liquor and the charring products. CONCLUSION: The different processing methods have certain effect on the content of gallic acid and catechin in R. palametum.